Warning: This story contains major spoilers about X-Men: Apocalypse. Read at your own risk.

The future of the X-Men franchise is taking shape. Beyond the announcements of Wolverine 3, Deadpool 2, the delayed Gambit, and New Mutants, an X-Force movie has been rumored for some time. Sophie Turner, too, teased the films’ return to The Dark Phoenix Saga, backed by her fiery moment in X-Men: Apocalypse. But the latest X-Men film offers more clues to what’s coming with the post-credits scene.

Those who stayed until the end of the credits saw a scene at Stryker’s Weapon X facility at Alkali Lake. While the janitorial staff cleaned up the bloody mess left behind by the feral Wolverine, a group of suits, one carrying a briefcase, marched to the mutant’s holding cell. There they revealed x-rays of Wolverine’s adamantium skeleton and a storage unit full of his DNA. One of the mysterious figures grabbed a vial of his blood marked Weapon X and placed it in the briefcase marked Essex Corp. with other different colored vials.

What does this all mean? Who were those suits? Why would they want Wolverine’s blood? If you’re still scratching your head, here’s a deeper dive into the Apocalypse post-credits scene.

Let’s start with the big reveal: Essex Corp. The name likely refers to Nathaniel Essex, a comic book character who has a much more familiar name — Mr. Sinister, a mad-scientist type geneticist. In the comics, he encountered Apocalypse in the 19th century. After the pair bonded over their obsession of Charles Darwin’s “survival of the fittest” theory of evolution, Apocalypse mutated Essex into the white-skinned, immortal mutant Mr. Sinister.

It may not be a coincidence, then, that Apocalypse was introduced in the latest X-Men film. It also may not be a coincidence that the Deadpool post-credits scene announced the mutant Cable for the sequel, as Sinister had a hand in creating him.

Sinister’s primary pursuit is finding the right combination of genes to create the ultimate mutant. He thought he found them in Jean Grey and Cyclops, and tricked Cyclops into sleeping with a clone of Jean. The ruse was eventually discovered, but not before he conceived a child who would grow up to become Cable. The bionic-armed merc has a complex story arc in which he travels to the future and comes back as a grown man to fight Apocalypse and lead the New Mutants and, later, the X-Force.

As demonstrated with Jean, Sinister’s other favored habit is cloning, which may speak to the other vials in the Essex Corp. briefcase. For those unfamiliar, clones of Wolverine were created in the comics out of attempts to recreate the Weapon X experiment. The most famous of these clones is X-23, a.k.a. Laura Kinney.

Unconfirmed rumors litter the web of the character’s possible involvement in Wolverine 3, and director Bryan Singer teased to Fandango that he pitched a “female” Wolverine to Fox. Sinister was not part of X-23’s creation in the comics, but he does have a connection to Weapon X. Sinister joined the program in later stories under the name Dr. Robert Windsor. His goal was to free the mutants from their grasp only to keep them as his own personal test subjects.

At the very least, the contents of the Essex Corp. briefcase suggest Wolverine isn’t the only secret mutant experiment.

Another question to consider is whether the post-credits scene has any connection to Wolverine 3, the next film in the X-Men slate (opening March 3, 2017). Boyd Holbrook of Netflix’s Narcos joined the cast as the lead villain, described as head of security for a global organization. Might this global organization be Essex Corp.? Elsewhere, The Hollywood Reporter was the first on the news of Richard E. Grant, who is reportedly playing a mad scientist of sorts.

We know the film, which still doesn’t have a title, is an R-rated story set in the future, which Hugh Jackman teased is based on the Old Man Logan comics. James Mangold returns to direct with a script by David James Kelly.